Fungicide

ABSTRACT

A FUNGICIDE FOR PROTECTING WOOD COMPRISING AN AQUEOUS SOLUTION OF AN ALKALI METAL HYDROXIDE, A METAL HYDROXIDE  0002SO FORMING HYDROXO ANIONS, AND AN ALKALI METAL SALT OR AMMONIUM SALT OF N-NITROSO-N-CYCLOHEXYLHYDROXYLAMINE, AND A PROCESS FOR PROTECTING WOOD AGAINST FUNGUS ATTACK BY TREATMENT WITH THIS FUNGICIDE.

US. Cl. 106-15 AF 4 Claims ABSTRACT OF THE DISCLOSURE A fungicide for protecting wood comprising an aqueous solution of an alkali metal hydroxide, a metal hydroxide forming hydroxo anions, and an alkali metal salt or ammonium salt of N-nitroso N cyclohexylhydroxylamine, and a process for protecting wood against fungus attack by treatment with this fungicide.

[RELATED APPLICATION This application is a division of our copending application Ser. No. 883,639, filed Dec. 9, 1969, now US. Pat. No. 3,725,544.

The invention relates to a fungicide which is suitable for protecting wood.

It is known to protect wood against fungus attack by treating the wood with numerous inorganic or organic compounds as the wood may otherwise be quickly destroyed. However, many of these compounds are washed out or evaporate out of the wood after a certain length of time. It is also known that the alkali metal salts of N- nitroso-N-cyclohexylhydroxylamine are fungicidally effective.

We have now found that the disadvantages mentioned above do not occur when a fungicide is used which comprises an aqueous solution of an alkali metal hydroxide, a metal hydroxide forming hydroxo anions, and an alkali metal salt or an ammonium salt of N-nitrosoN-cyclohexylhydroxylamine. The term a metal hydroxide forming hydroxo anions is taken to mean a metal hydroxide forming, with an alkali metal hydroxide, for example Zn(OH),'-, Cr(0H) Pb(OH) Sn(OH) and preferably aluminum hydroxo anions. It is not necessary for the aqueous solution of the fungicide to be completely clear; the ingredients of the solution need only be substantially dissolved. A small undissolved residue possibly originating from impurities does not impair the fungicidal action. The term alkali metal hydroxide is taken to mean sodium hydroxide and potassium hydroxide. The term alkali metal salts of N-nitroso N cyclohexylhydroxylamine is taken to mean its sodium salts and potassium salts. Single compounds or mixtures thereof may of course, be replaced by substances which in solution give the corresponding compounds. For instance, an alkali metal salt of N-nitrosohydroxylamine may be replaced by a mixture of N-nitrosohydroxylamine and an alkali metal hydroxide, or the mixture of an alkali metal hydroxide and aluminum hydroxide may be replaced by alkali metal aluminate or by an alkali metal hydroxide and a water-soluble aluminum compound, especially an aluminum salt. The same applies, mutatis mutandis, for the replacement of the other, metal hydroxides by the corresponding water-soluble metal compounds, particularly metal salts. The wood may be treated with the fungicide by either impregnating (with or without the application of pressure), spraying or coating with the solution the wood material to be protected and by subsequently drying the wood. During drying, the sparingly soluble metal salt of N nitrosocyclohexylhydroxylamine is formed, by the action of the natural carbon dioxide content of the air and by the action of the natural acids in the wood, from thesoluble alkali metal salts or ammonium salts of N-nitrosocyclohexylhydroxylariiihe and from the alkali metal hydroxo salts, thus providing the wood with lasting protection against fungus a tack. Instead of employing natural carbon dioxide, it is also possible to treat the impregnated wood with carbon dioxide or other inorganic or organic acids, e.g. dilute sulfiiric acid or acetic acid, or with acid-reacting salts, e.g. ammonium chloride. It is further possible to add the fungicide to a binder for wood-base materials, e.g. to a wood glue for the manufacture of chipboard, protecting irr'thisj way the finished chipboard against fungus attack. For this purpose, the fungicide as such, or its individual components separately, may be added to the wood glue eithgr during or after its manufacture.

" Generally, alkali metal aluminate and the alkali metal salt or ammonium salt of N-nitrosocyclohexylhydroxylamine are used in stoichiometric amounts (molar ratio 1:3) for the production of the fungicide. However, it is alsopossible to use different amounts. When manufacturing the fungicide, about 1 to 50 parts by weight of alkali metal h ydroxide, 1 to 50 parts by weight of metal hydroxide and 1 to 100 parts by weight of water may be used per part by weight of the alkali metaLsalt or ammonium salt of N-nitrosocyclohexylhydroxylamine.

The amount of fungicide necessary for coating the wood (dry substance) may be form 25 to'1,250 g./m. particularly 250 g./m. As it is desirable .when impregnating tlfe wood to achieve complete penetration, a very large excess of fungicide solution must always be used.

i It is important for the storage stability of the fungicide that the pH should be adjusted to between 9 and 12, preferably 11.

The solutions may for example be prepared as follows:

Aluminum sulfate is dissolved in water in an apparatus equipped with a stirrer; alkali metal hydroxide is then added in at least such an amount necessary to form the aluminate. The alkali metal salt orammonium salt of .N-nitrosocyclohexylhydroxylamine is then introduced into this solution while stirring. The solution is subsequently adjusted with an acid or a base to thefdesired pH.

The parts in the following examples are parts by weight.

EXAMPLE 1 Preparation of a wood glue 588 parts of phenol, 962 parts of 39% formaldehyde and 94 parts of water are placed, while stirring, into a glass flask. One half of 525 parts of 50% by weight daustic potash solution, in which 22.5, parts of aluminum hydroxide has been dissolved, is carefully metered in. After .eibb, addition, the reaction is awaitedand the reaction mixture is, if necessary, cooled. Condensation is carried outifor 30 minutes at 60 to 65 C.; the remainder of the caustic potash solution is then carefuli'y added. Condensation is continued by heating to boiling temperature until the glue has a viscosity of 35 to 40 seconds (DIN beaker 4). The mixture is cooled to 25 to 30 C., and 232 parts of 39% formaldehyde and 50 parts of the potassium salt of N-nitrosocyclohexylhydroxylamine are added to it.

Preparation of a 5% fungicide solution 198 ml. of 2 N caustic soda solution is added to 30.4 parts of Al (SO 18H O which has been dissolved in 400 parts of water. While' stirring, 55.5 parts of the potas sium salt of N-nitrosocyclohexylhydroxylamine is dissolved in this solution; the pH is adjusted to 10.5 by

3 adding 150 ml. of N/l H SO and the solution is made up to 1,000 parts with water. Fungicide solutions having a lower active ingredient content (0.2; 0.5; 1 and 2% by weight solutions) may be prepared similarly.

Preparation of a 2% fungicide solution Preparation of a 2% fungicide solution '25 ml. of N caustic soda solution is added to 1.4 parts of SnCl .2'H O dissolved in parts of water. While stirring, 2 parts of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamirie is dissolved in this solution and the whole made up to 100 parts with water.

Preparation of a 1% fungicide solution 34.5 ml. of 5 N caustic soda solution is added to 2.25 parts of Pb (CH C0O) .3H =O dissolved in 10 parts of water. While stirring, 1 part of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamine is dissolved in this solution and the whole made up to 100 parts with water.

Blocks of spruce and pine wood measuring 50 x 25 x mm. were evenly coated with 0.2, 0.5, 1 and 2 wt. percent fungicide solutions and dried for several days in the air. In one series of experiments the specimens were then exposed to attack by the ligniperdous fungus Coniophofa cerebella, while the specimens for a second series of experiments were placed, before exposure to the fungus, for three days in running tap water to test the stability of the fungicide impregnation. The experiments on resistance to fungus attack were carried out in glass dishes (diameter 15 cm.; height 3 cm.), the specimens being placed upon a malt nutrient agar covered with the fungus used for test purposes and beingexposed at about 22 C. to the fungus attack for a period of 12 weeks.

Fungus used for purposes of the test: Coniophora care bella Extent oi iungus Extent oi fungus development on the development on the specimens after specimens after the the number number of weeks of weeks indicated (3 days Percentage indicated in water) active ingredient in the solution Spccimon/ of 4 8 l2 4 8 12 wks. wks. wks. wks. wks. wks.

Untreate Untreated mwoooooooo eeeeoooooooc QIWOOOOOOr-neeeeoooclocn-nenuOQOOQoHM weeocoocd'im Nora: Ozno fungus growth on the specimen; 13:s1ight to complete cover of the specimen with fungus mycelium.

EXAMPLE 2 4 gredients (0.2; 0.5; 1 and 2% by weight solutions) may be prepared similarly.

Blocks of spruce and pine wood measuring 50 x 25 x 15 mm. were freed in vacuo in an autoclave of the air in them and were impregnated at 10 atmospheres of nitrogen with a 2 wt. percent, 1 wt. percent, 0.5 wt. percent and 0.2 wt. percent aqueous solution of the sodium salt of N-nitrosocyclohexylhydroxylamine containing a somewhat more than stoichiometric amount of sodium aluminate. Some of the blocks were dried in the air, some were treated for 30 minutes in an autoclave at 10 atmospheres of CO and the remainder treated for 30 minutes in an autoclave at 10 atmospheres of nitrogen with dilute sulfuric acid.

1;ungus used for purposes of the test: Coniophora cereel a Extent 0! fungus Extent oi fungus deveio ment on the development on the spec mans after specimens after the the number number oi weeks Percentage of weeks indicated (3 days active indicated in water) Spruce wood ingredient specimen/type in the 4 8 12 4 8 12 of treatment solution wks. wks, wks. wks. wks. wire.

(a) Only air drying 0. 2 0 0 0 0 (b) Autoclave 0. 2 0 0 0 0 0 0 10 atm. C (c) Autoclave dilute H. 0. 2 0 0 0 0 0 0 a) 0. 5 0 0 0 0 0 0 0. 5 0 0 0 0 0 0 0. 5 0 0 0 0 0 0 1. 0 0 0 0 0 0 0 1.0 0 0 0 0 0 0 1.0 0 0 0 O 0 0 2. 0 0 0 0 0 0 0 2. 0 0 0 0 0 0 0 2. 0 0 0 0 0 0 0 ed 8 8 3 3 8 3 "ed 8 3 3 8 8 8 "ed 8 3 3 8 0 3 News: 0=no fungus growth on the specimen; l iimelight to complete cover 0 the specimen with fungus myceltum.

The invention is hereby claimed as follows: 1. A fungicide for protecting wood comprising an aqueous solution of (I) (a) sodium or potassium aluminate or (b) a mixture of sodium or potassium hydroxide and the hydroxide of aluminum, zinc, chromium, lead or tin, and (II) the sodium, potassium or ammonium salt of N- nitroso-N-cyclohexylhydroxylamine in proportions by Weight of 1-50 parts of (I) per part of (II) and 1-100 parts of water per part of (II).

2. A fungicide as claimed in claim 1, (I) being the mixture (b) embodying aluminum hydroxide.

3. A fungicide as claimed in claim 1 wherein (I) is sodium aluminate.

i. Wood glue having admixed therein an eifective fungicidal amount relative to the fungus Coniophora cerebella of the fungicide as claimed in claim 1.

References Cited UNITED STATES PATENTS 2,954,314 9/1960 Metzger et al. 106-15 AF 3,019,146 1/1962 Haigh et al. 106-15 AF 3,305,298 2/1967 Chapman et al. 106-15 AF HARRY WONG, 1a., Primary Examiner U.S. Cl. X.R. 

